Houston lifts boil water notice, confirms tap water is safe to drink

Houston has lifted its boil water notice, two days after a power outage affecting one of the city's water purification plants raised concerns about contaminants potentially lingering in the main water supply. The Texas Commission on Environmental Quality conducted water quality tests while the notice was still in effect, and confirmed that tap water meets regulatory standards, the city of Houston said in a news release.

"Houston Water has taken the necessary corrective actions to restore the quality of the water distributed by this public water system used for drinking water or human consumption purposes," the city said. 

Before returning to normal use, Houston Water customers should first "flush" their home water systems by running faucets on cold for at least one minute, and making and discarding several batches of ice from their automatic ice machines to trigger water treatment softeners through a regeneration cycle, according to the city.

All of Houston's public schools will remain closed for a second day Tuesday, after millions of residents were advised to boil their drinking water in the aftermath of a power outage at one of the city's purification plants. 

Houston officials issued a formal boil water notice on Sunday, when the outage caused water pressure at the East Water Purification Plant — which feeds into the city's main water system, serving about 2.2 million customers — to drop below regulators' required minimum of 20 PSI. Lower water pressure at the purification plant increases the risks of bacteria and other harmful microbes entering drinking water supplies. 

Although Mayor Sylvester Turner said Monday that water was likely safe to use again, the city's testing protocols mean its boil water notice will remain in effect until at least Tuesday.

The Houston Independent School District announced building closures shortly after the notice was issued on Sunday evening, and said on Twitter it would continue to monitor the situation. The district said Monday afternoon schools would remain closed Tuesday.

"This decision has been made due to the logistical challenges caused by the notice. Those challenges prevent the district from being able to provide meals for its students and ensure safe water is available for students and staff," the district wrote on Twitter.

The city issued a news release on Sunday alerting residents to a pressure drop at the purification plant. It recommended that everyone living in the affected area refrain from drinking tap water without first bringing it to a "vigorous rolling boil" and then allowing it to continue to boil for another two minutes. People should follow this protocol before using the water to brush their teeth, or to wash their hands and face, the city said, noting that people with weakened immune systems are particularly susceptible to harmful bacteria that could be present in the water supply.

"To ensure destruction of all harmful bacteria and other microbes, water for drinking, cooking, and ice making should be boiled and cooled prior to use for drinking water or human consumption purposes," the boil water notice stated. "In lieu of boiling, individuals may purchase bottled water or obtain water from some other suitable source for drinking water or human consumption purposes."

Late on Sunday night, Mayor Turner said that city officials believed the water was safe to use, but regulatory requirements mandate that a boil water notice remains in effect until the Texas Commission on Environmental Quality has completed repeat testing on water samples, and confirmed they are not contaminated.

"We believe the water is safe but based on regulatory requirements when pressure drops below 20 psi we are obligated to issue a boil water notice. The City is submitting its plan to TCEQ for approval tonight," the mayor tweeted. "Water samples will subsequently follow and hopefully we will get the all clear from TCEQ. The City has to wait 24 hours from that point before the boil water notice is suspended. The earliest would be tomorrow night or very early Tuesday morning."

In:
• Houston
• Texas
• Drinking Water
• Education